9G HOMES WITHOUT HANDS. 



In the winter time, each of these holes is occupied by a speci- 

 men of the Helix saxicava, a small snail, closely resembling the 

 common banded snail of our hedges {Helix nemoralis), and it is 

 thought that the holes are excavated by the snail which inhabits 

 them. Mr. Hancock, who has lately re-opened in the columns 

 of the Field newspaper a controveKsy respecting these snails, 

 which was initiated in 18U9, is of opinion that the snails really 

 form the hole, and that they burrow at the average rate of half 

 an inch per annum. The late Dean Buckland was of the same 

 opinion. Other naturalists, however, think that the holes were 

 originally excavated by pholades and other marine molluscs 

 when the rocks in question formed part of the ocean bed, and 

 that the snails merely inhabit the ready-formed holes. Mr. 

 Pinkerton upholds this opinion, and states that at least three 

 other species of helix possess similar habits, the garden and the 

 banded snail being among the number. 



I have compared the burrows of the moUusc, which we will 

 call the Boring Snail, with those of the pholas and lithodomus, 

 both of which will be presently described, and find that there is 

 no resemblance in their forms, the shape and direction of the 

 holes being evidently caused by an animal of no great length 

 in proportion to its width. In my own specimen, every hole is 

 contracted at irregular intervals, forming a succession of rounded 

 hollows. If we return to our lump of putty, we may form 

 the holes made by the thumb into a very good imitation of those 

 in which the Boring Snail lives. After the thumb has been 

 pushed into the putty and well twisted round, put in the fore- 

 finger as far as the first joint and turn it round so as to make 

 a rounded hollow. Push the finger into the hole as far as the 

 second joint, and repeat the process. Now introduce the whole 

 of the finger, enlarge the extremity of the hole and round it 

 carefully, when there will be a very correct representation of 

 the tunnel formed in the rock. 



Granting that the snail really does form the burrow, we have 

 still to discover the mode of working. Mr. Hancock says that 

 it must do so by means of an acid secretion proceeding from 

 the foot, which corrodes the rock and renders it easy to be 

 washed away. If the snail be removed and placed on litmus 

 paper, the ruddy violet colour which at once tinges the paper 

 shows that there is acid of some kind, and if the paper be 



